I usually only wear a face cover when I'm shovelling during that Jan-Feb period when it gets to superlow...that point when the F temp is colder than the C temp...somewhere around -40F - -45F. Seems like every once in a while we get a cold boost to around -60F at night...but usually only about once a winter (oh yeah, that's -60F air temp, not wind chill...every day on the plain is -60F windchill).